Objective：To explore the relationship between blood pressure variability (BPV) induced by nocturnal hypoxia events and vascular endothelial function in OSA patients. Methods：Between February 2022 and April 2023，a total of 131 moderate-to-severe OSA patients were studied from the departments of Sleep Medicine Centers three different hospitals，including the Affiliated Huaian No.1 People’s Hospital of Nanjing Medical University. All participants underwent polysomnography (PSG)，and blood pressure (BP) was full night monitored continuously and synchronized with PSG. The BPV induced by hypoxia was calculated：the gap between the peak SBP and the lowest SBP during a hypoxia event，which was used to reflect the amplitude of BP fluctuation (△BP)；the number of which≥10 mmHg per hour/oxygen desaturation index (ODI) indicated the percentage of BP fluctuations. Endothelial function was assessed by Flow-Mediated Dilation (FMD). Patients were divided into normal endothelial function group (n=70) and endothelial dysfunction group (n=61) according to FMD value. The BPV parameters were compared and the related factors of BPV were also analyzed. Results：There were no differences in age，sex distribution，body mass index，OSA severity etc. Compared with the normal endothelial function group，the endothelial dysfunction group exhibited more higher BPV induced by hypoxia events [nocturnal systolic peak BP (152.0±7.2) vs (148.1±8.8) mmHg，nocturnal diastolic peak BP (89.8±5.7) vs (87.5±6.6) mmHg，△BP (15.3±2.9) vs (13.3±2.7) mmHg，the percentage of BP fluctuations [(63.5±14.3) vs (44.8±10.7) %，all P＜0.05] and Endothelin-1 [(50.7±7.0) vs (47.8±8.5) ng/L，P＜0.05]. After adjusting the baseline data of patients，the line regression model showed that the nocturnal SBP peak，the percentage of BP fluctuations and △BP were all positively correlated with FMD (all P＜0.05). Conclusion：For moderate-to-severe OSA patients，the elevation of BPV induced by hypoxia events is closely correlated to vascular endothelial dysfunction.